Bigdogtrucker Posted August 15, 2014 Share Posted August 15, 2014 Are they universal?Finally brought my R model home from storage today,leaks air pretty bad from the parking valve button.After sitting all these months she cranked right up soon as I turned the key . 1 Quote Link to comment https://www.bigmacktrucks.com/topic/36709-parking-brake-valve/ Share on other sites More sharing options...
doubleclutchinweasel Posted August 15, 2014 Share Posted August 15, 2014 There are a few different valves.If you look at the valve, there usually is a tag on it with a number. That number is a big help!My parking brake valve incorporated an anti-compounding valve. Very handy.You can download the Bendix handbook, which has lots of good stuff in it.I redid virtually my whole system. So, let me know if I can help. 1 Quote "Eagles may soar, but weasels don't get sucked into jet engines." Link to comment https://www.bigmacktrucks.com/topic/36709-parking-brake-valve/#findComment-256135 Share on other sites More sharing options...
Bigdogtrucker Posted August 16, 2014 Author Share Posted August 16, 2014 Thanks,soon as I get some time i'll pull it apart. Quote Link to comment https://www.bigmacktrucks.com/topic/36709-parking-brake-valve/#findComment-256136 Share on other sites More sharing options...
1957B61Vt Posted August 16, 2014 Share Posted August 16, 2014 Nice to see it againGoing to keep it bigdog ?Hope so I like that truck.Be nice to see it all cleaned upAnd some paint on it Steve 1 Quote Link to comment https://www.bigmacktrucks.com/topic/36709-parking-brake-valve/#findComment-256137 Share on other sites More sharing options...
Bigdogtrucker Posted August 16, 2014 Author Share Posted August 16, 2014 I've had a LOT of offers on it,somehow resisted each time...I deff. wouldn't be able to replace easily.Plans are to patch up the roof skin for now(only real bad part of the cab)and clean the truck up a bit.Paint is not in the picture right now,so i'll be giving it a CLR bath and a coating of Linseed oil .Just want to get everything working/serviced and preserve it where it is right now.Just tried the lights and to my surprise they all work,needs 2 or bulbs. 1 1 Quote Link to comment https://www.bigmacktrucks.com/topic/36709-parking-brake-valve/#findComment-256139 Share on other sites More sharing options...
doubleclutchinweasel Posted August 16, 2014 Share Posted August 16, 2014 That's how I'm approaching mine...keep it running first, & make it pretty later.Preservation first: restoration second. 1 1 Quote "Eagles may soar, but weasels don't get sucked into jet engines." Link to comment https://www.bigmacktrucks.com/topic/36709-parking-brake-valve/#findComment-256142 Share on other sites More sharing options...
Bigdogtrucker Posted August 16, 2014 Author Share Posted August 16, 2014 No doubt,i love patina anyways . Quote Link to comment https://www.bigmacktrucks.com/topic/36709-parking-brake-valve/#findComment-256146 Share on other sites More sharing options...
Maddog13407 Posted August 16, 2014 Share Posted August 16, 2014 ship the truck up here bigdog. ill fix that valve right up and park it in my storage lot..... 1 Quote Link to comment https://www.bigmacktrucks.com/topic/36709-parking-brake-valve/#findComment-256150 Share on other sites More sharing options...
doubleclutchinweasel Posted August 16, 2014 Share Posted August 16, 2014 Here is a picture of my parking brake valve, taken as I was changing it out. If you look closely, you can see part of the ID number stamped into the side.The most common "yellow button" valves were the PP1 and PP2.The PP2 has the anti-compounding feature, which keeps you from adding brake force to the parking brake if you press the pedal when the spring brakes are applied. It does this simply by porting some air to the "release" side of the parking brake at the same time the service brake is applied. Pretty simple, and pretty clever.I am also attaching a couple of .pdf files for these 2 common valves. Maybe you can find your number listed!PP-1.pdfPP-2.pdf 1 Quote "Eagles may soar, but weasels don't get sucked into jet engines." Link to comment https://www.bigmacktrucks.com/topic/36709-parking-brake-valve/#findComment-256210 Share on other sites More sharing options...
Bigdogtrucker Posted August 16, 2014 Author Share Posted August 16, 2014 Thanks dcw! Quote Link to comment https://www.bigmacktrucks.com/topic/36709-parking-brake-valve/#findComment-256216 Share on other sites More sharing options...
doubleclutchinweasel Posted August 16, 2014 Share Posted August 16, 2014 Thanks dcw!Sure thing, 'Dog.That valve was the first piece I changed on mine when I got it home. It was leaking. Could turn it and make it better or worse. I got quite an education in Mack air brakes. Almost every piece of mine has been changed. Even upgraded from DD3 parking brakes to spring brakes.Look up my content. There are a couple of posts about the brake upgrade. And, there's one entitled "sometimes I wonder" that shows everything I had done up to that time.Let me know if I can help with the air brake circuitry. 1 Quote "Eagles may soar, but weasels don't get sucked into jet engines." Link to comment https://www.bigmacktrucks.com/topic/36709-parking-brake-valve/#findComment-256219 Share on other sites More sharing options...
doubleclutchinweasel Posted August 16, 2014 Share Posted August 16, 2014 I just noticed the V8 emblem on the hood!What is the model number? R615? Quote "Eagles may soar, but weasels don't get sucked into jet engines." Link to comment https://www.bigmacktrucks.com/topic/36709-parking-brake-valve/#findComment-256231 Share on other sites More sharing options...
Bigdogtrucker Posted August 17, 2014 Author Share Posted August 17, 2014 R795ST .Just had her running for a while,longest yet.Air leak is coming from behind the cab when I hit the trolley or the yellow! Quote Link to comment https://www.bigmacktrucks.com/topic/36709-parking-brake-valve/#findComment-256236 Share on other sites More sharing options...
doubleclutchinweasel Posted August 17, 2014 Share Posted August 17, 2014 Oh. A 700! And with big 8. Awesome. Drove one years ago (only once or twice). It had the 2-stick 6-speed. Stout truck.Always thought a 700 cockpit looked kinda cool with the shifters going out the front of the floorboards!That air leak wouldn't be coming out of the tractor protection valve at the rear of the cab, would it? Quote "Eagles may soar, but weasels don't get sucked into jet engines." Link to comment https://www.bigmacktrucks.com/topic/36709-parking-brake-valve/#findComment-256280 Share on other sites More sharing options...
Bigdogtrucker Posted August 17, 2014 Author Share Posted August 17, 2014 Blue trailer air line is split,comes out of there if you apply foot brake,trolley or yellow button.I have little experience with trailer lines!(triaxle dump driver) Quote Link to comment https://www.bigmacktrucks.com/topic/36709-parking-brake-valve/#findComment-256295 Share on other sites More sharing options...
doubleclutchinweasel Posted August 17, 2014 Share Posted August 17, 2014 I thought you would only get air out of the blue (service) line if you applied service brakes (foot or trolley). When you push the parking brake release (yellow) down, and the trailer supply (red) down, you should get air to the red (emergency) line.May have to disconnect the lines to see if there is a problem with the tractor plumbing, or if there is air returning from the trailer somehow. Quote "Eagles may soar, but weasels don't get sucked into jet engines." Link to comment https://www.bigmacktrucks.com/topic/36709-parking-brake-valve/#findComment-256298 Share on other sites More sharing options...
Bigdogtrucker Posted August 17, 2014 Author Share Posted August 17, 2014 No trailer hooked to it.Worked perfect when it was parked,all original nothings been touched also. Quote Link to comment https://www.bigmacktrucks.com/topic/36709-parking-brake-valve/#findComment-256300 Share on other sites More sharing options...
doubleclutchinweasel Posted August 17, 2014 Share Posted August 17, 2014 The plumbing on those old trucks was fairly simple.Jut map out a circuit, and you should be able to trace it out.I have diagrams, but they are all '72 & earlier. Quote "Eagles may soar, but weasels don't get sucked into jet engines." Link to comment https://www.bigmacktrucks.com/topic/36709-parking-brake-valve/#findComment-256302 Share on other sites More sharing options...
gearhead204 Posted August 17, 2014 Share Posted August 17, 2014 bdt is that a 3 valve system red yellow blue knob? or valve Yellow /red? if its a three valve you will have air in the trailer lines any time the red and yellow knobs are charged.( and more than sixty psi in the system) Quote Link to comment https://www.bigmacktrucks.com/topic/36709-parking-brake-valve/#findComment-256332 Share on other sites More sharing options...
Bigdogtrucker Posted August 17, 2014 Author Share Posted August 17, 2014 Red/yellow Quote Link to comment https://www.bigmacktrucks.com/topic/36709-parking-brake-valve/#findComment-256344 Share on other sites More sharing options...
doubleclutchinweasel Posted August 17, 2014 Share Posted August 17, 2014 Two ways that can work. 1. When you pull the yellow, the air is dumped off both circuits, & the red stays up. When you push the yellow down, both circuits are charged, releasing the brakes.2. When you pull the yellow, air is dumped off the tractor side, & the red pops out automatically, dumping the air off the trailer circuit. To release, you have to push the yellow in and then the red.But, with the red out, there should be no air going to the trailer "emergency" or "pilot" line. However, regardless of pilot pressure, applying the treadle or trolley valves will apply pressue to the trailer "service" or "signal" line.The air from the red goes to one side of the tractor protection valve. Air from the trolley or treadle valve goes to the other side (the one with the quick-release diaphragm).Without a trailer, the red should be out, cutting off the air to the t-p valve.Since I don't pull a trailer with mine, I removed the trailer connection hoses, & plugged the connections with pipe plugs. 1 Quote "Eagles may soar, but weasels don't get sucked into jet engines." Link to comment https://www.bigmacktrucks.com/topic/36709-parking-brake-valve/#findComment-256354 Share on other sites More sharing options...
Bigdogtrucker Posted August 18, 2014 Author Share Posted August 18, 2014 Looks like the air valve behind the cab is the problem.I'm gonna plug the supply lines for now. Quote Link to comment https://www.bigmacktrucks.com/topic/36709-parking-brake-valve/#findComment-256379 Share on other sites More sharing options...
doubleclutchinweasel Posted August 18, 2014 Share Posted August 18, 2014 That is probably your tractor protection valve. It is supposed to close if you lose a hose on the trailer and prevent all the air in the tractor system from escaping. When you pull the red knob, this should close the valve. However, when you apply treadle or trolley valve, air will still be supplied TO the service side of that valve. But, if I remember correctly, it should not pass through (or I could be wrong about that...been a while).If plugging it does the trick, excellent. If not, you could always plug the outlet at the treadle valve which goes to that vavle...or simply cap the line. This would prevent any air from the service brakes from going to the T-P valve.Sounds like you have it in hand, 1 Quote "Eagles may soar, but weasels don't get sucked into jet engines." Link to comment https://www.bigmacktrucks.com/topic/36709-parking-brake-valve/#findComment-256404 Share on other sites More sharing options...
Bigdogtrucker Posted August 18, 2014 Author Share Posted August 18, 2014 Pretty sure that's where the issue is,i'll let you know what happens. Quote Link to comment https://www.bigmacktrucks.com/topic/36709-parking-brake-valve/#findComment-256414 Share on other sites More sharing options...
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